[libcxx-commits] [libcxx] 0a92e07 - [libc++] Use __unwrap_iter_impl for both unwrapping and rewrapping
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Jul 14 11:01:24 PDT 2022
Author: Nikolas Klauser
Date: 2022-07-14T20:01:19+02:00
New Revision: 0a92e0728c8c5b6b36adff6ebaa2b8cddd44298c
URL: https://github.com/llvm/llvm-project/commit/0a92e0728c8c5b6b36adff6ebaa2b8cddd44298c
DIFF: https://github.com/llvm/llvm-project/commit/0a92e0728c8c5b6b36adff6ebaa2b8cddd44298c.diff
LOG: [libc++] Use __unwrap_iter_impl for both unwrapping and rewrapping
Reviewed By: ldionne, #libc
Spies: arichardson, sstefan1, libcxx-commits
Differential Revision: https://reviews.llvm.org/D129039
Added:
Modified:
libcxx/include/__algorithm/unwrap_iter.h
libcxx/include/__iterator/reverse_iterator.h
libcxx/utils/libcxx/test/params.py
Removed:
################################################################################
diff --git a/libcxx/include/__algorithm/unwrap_iter.h b/libcxx/include/__algorithm/unwrap_iter.h
index 7d1807b7bbf93..fa9a8fbf2dde2 100644
--- a/libcxx/include/__algorithm/unwrap_iter.h
+++ b/libcxx/include/__algorithm/unwrap_iter.h
@@ -12,6 +12,7 @@
#include <__config>
#include <__iterator/iterator_traits.h>
#include <__memory/pointer_traits.h>
+#include <__utility/move.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -20,77 +21,50 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-// The job of __unwrap_iter is to lower contiguous iterators (such as
-// vector<T>::iterator) into pointers, to reduce the number of template
-// instantiations and to enable pointer-based optimizations e.g. in std::copy.
-// For iterators that are not contiguous, it must be a no-op.
+// TODO: Change the name of __unwrap_iter_impl to something more appropriate
+// The job of __unwrap_iter is to remove iterator wrappers (like reverse_iterator or __wrap_iter),
+// to reduce the number of template instantiations and to enable pointer-based optimizations e.g. in std::copy.
// In debug mode, we don't do this.
//
-// __unwrap_iter is non-constexpr for user-defined iterators whose
-// `to_address` and/or `operator->` is non-constexpr. This is okay; but we
-// try to avoid doing __unwrap_iter in constant-evaluated contexts anyway.
-//
// Some algorithms (e.g. std::copy, but not std::sort) need to convert an
-// "unwrapped" result back into a contiguous iterator. Since contiguous iterators
-// are random-access, we can do this portably using iterator arithmetic; this
-// is the job of __rewrap_iter.
+// "unwrapped" result back into the original iterator type. Doing that is the job of __rewrap_iter.
+// Default case - we can't unwrap anything
template <class _Iter, bool = __is_cpp17_contiguous_iterator<_Iter>::value>
struct __unwrap_iter_impl {
- static _LIBCPP_CONSTEXPR _Iter
- __apply(_Iter __i) _NOEXCEPT {
- return __i;
- }
+ static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap(_Iter, _Iter __iter) { return __iter; }
+ static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __unwrap(_Iter __i) _NOEXCEPT { return __i; }
};
#ifndef _LIBCPP_ENABLE_DEBUG_MODE
+// It's a contiguous iterator, so we can use a raw pointer instead
template <class _Iter>
struct __unwrap_iter_impl<_Iter, true> {
- static _LIBCPP_CONSTEXPR decltype(_VSTD::__to_address(declval<_Iter>()))
- __apply(_Iter __i) _NOEXCEPT {
- return _VSTD::__to_address(__i);
- }
-};
+ using _ToAddressT = decltype(std::__to_address(std::declval<_Iter>()));
-#endif // !_LIBCPP_ENABLE_DEBUG_MODE
-
-template<class _Iter, class _Impl = __unwrap_iter_impl<_Iter> >
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
-decltype(_Impl::__apply(declval<_Iter>()))
-__unwrap_iter(_Iter __i) _NOEXCEPT
-{
- return _Impl::__apply(__i);
-}
-
-template <class _OrigIter, class _UnwrappedIter>
-struct __rewrap_iter_impl {
- static _LIBCPP_CONSTEXPR _OrigIter __apply(_OrigIter __first, _UnwrappedIter __result) {
- // Precondition: __result is reachable from __first
- // Precondition: _OrigIter is a contiguous iterator
- return __first + (__result - std::__unwrap_iter(__first));
+ static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Iter __rewrap(_Iter __orig_iter, _ToAddressT __unwrapped_iter) {
+ return __orig_iter + (__unwrapped_iter - std::__to_address(__orig_iter));
}
-};
-template <class _OrigIter>
-struct __rewrap_iter_impl<_OrigIter, _OrigIter> {
- static _LIBCPP_CONSTEXPR _OrigIter __apply(_OrigIter, _OrigIter __result) {
- return __result;
+ static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ToAddressT __unwrap(_Iter __i) _NOEXCEPT {
+ return std::__to_address(__i);
}
};
-template<class _OrigIter>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
-_OrigIter __rewrap_iter(_OrigIter, _OrigIter __result)
-{
- return __result;
+#endif // !_LIBCPP_ENABLE_DEBUG_MODE
+
+template<class _Iter,
+ class _Impl = __unwrap_iter_impl<_Iter>,
+ __enable_if_t<is_copy_constructible<_Iter>::value, int> = 0>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
+decltype(_Impl::__unwrap(std::declval<_Iter>())) __unwrap_iter(_Iter __i) _NOEXCEPT {
+ return _Impl::__unwrap(__i);
}
-template<class _OrigIter, class _UnwrappedIter, class _Impl = __rewrap_iter_impl<_OrigIter, _UnwrappedIter> >
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
-_OrigIter __rewrap_iter(_OrigIter __first, _UnwrappedIter __result)
-{
- return _Impl::__apply(__first, __result);
+template <class _OrigIter, class _Iter, class _Impl = __unwrap_iter_impl<_OrigIter> >
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _OrigIter __rewrap_iter(_OrigIter __orig_iter, _Iter __iter) _NOEXCEPT {
+ return _Impl::__rewrap(std::move(__orig_iter), std::move(__iter));
}
_LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__iterator/reverse_iterator.h b/libcxx/include/__iterator/reverse_iterator.h
index a915609dbe334..7f4ef3c3d503b 100644
--- a/libcxx/include/__iterator/reverse_iterator.h
+++ b/libcxx/include/__iterator/reverse_iterator.h
@@ -332,41 +332,16 @@ using _ReverseWrapper = reverse_iterator<reverse_iterator<_Iter> >;
template <class _Iter, bool __b>
struct __unwrap_iter_impl<_ReverseWrapper<_Iter>, __b> {
- static _LIBCPP_CONSTEXPR decltype(std::__unwrap_iter(std::declval<_Iter>()))
- __apply(_ReverseWrapper<_Iter> __i) _NOEXCEPT {
- return std::__unwrap_iter(__i.base().base());
- }
-};
-
-template <class _OrigIter, class _UnwrappedIter>
-struct __rewrap_iter_impl<_ReverseWrapper<_OrigIter>, _UnwrappedIter> {
- template <class _Iter>
- struct _ReverseWrapperCount {
- static _LIBCPP_CONSTEXPR const size_t value = 1;
- };
-
- template <class _Iter>
- struct _ReverseWrapperCount<_ReverseWrapper<_Iter> > {
- static _LIBCPP_CONSTEXPR const size_t value = 1 + _ReverseWrapperCount<_Iter>::value;
- };
-
- template <size_t _RewrapCount, class _OIter, class _UIter, __enable_if_t<_RewrapCount != 0, int> = 0>
- _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR _ReverseWrapper<_OIter> __rewrap(_ReverseWrapper<_OIter> __iter1,
- _UIter __iter2) {
- return _ReverseWrapper<_OIter>(
- reverse_iterator<_OIter>(__rewrap<_RewrapCount - 1>(__iter1.base().base(), __iter2)));
- }
+ using _UnwrappedIter = decltype(__unwrap_iter_impl<_Iter>::__unwrap(std::declval<_Iter>()));
- template <size_t _RewrapCount, class _OIter, class _UIter, __enable_if_t<_RewrapCount == 0, int> = 0>
- _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR decltype(std::__rewrap_iter(std::declval<_OIter>(),
- std::declval<_UIter>()))
- __rewrap(_OIter __iter1, _UIter __iter2) {
- return std::__rewrap_iter(__iter1, __iter2);
+ static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _ReverseWrapper<_Iter>
+ __rewrap(_ReverseWrapper<_Iter> __orig_iter, _UnwrappedIter __unwrapped_iter) {
+ return _ReverseWrapper<_Iter>(
+ reverse_iterator<_Iter>(__unwrap_iter_impl<_Iter>::__rewrap(__orig_iter.base().base(), __unwrapped_iter)));
}
- _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR _ReverseWrapper<_OrigIter> __apply(_ReverseWrapper<_OrigIter> __iter1,
- _UnwrappedIter __iter2) {
- return __rewrap<_ReverseWrapperCount<_OrigIter>::value>(__iter1, __iter2);
+ static _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _UnwrappedIter __unwrap(_ReverseWrapper<_Iter> __i) _NOEXCEPT {
+ return __unwrap_iter_impl<_Iter>::__unwrap(__i.base().base());
}
};
diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
index 22aa19ec0a26c..a4f4bf226d77f 100644
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -38,6 +38,9 @@
# TODO(mordante) investigate a solution for this issue.
'-Wno-tautological-compare',
+ # -Wstringop-overread seems to be a bit buggy currently
+ '-Wno-stringop-overread',
+
# These warnings should be enabled in order to support the MSVC
# team using the test suite; They enable the warnings below and
# expect the test suite to be clean.
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